Interest-computing machine.



No. 665,8. Patented Ian. I, |90I. L. M. LANDING.

INTEREST COMPUTING MACHINE.

(Application filed lily 25, 1900.)

2 Sheets-Sheet I.

(No Model.)

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No. 665,II8. .Patented Ian. I', I90I. L. M. LANDING.

INTEREST COMPUTING MACHINE.

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LARS M. LANDING, OF GLENWOOD, MINNESOTA.

INTEREST-COMPUTING MACHINE.

SPECIFICATION forming part of Letters Patent No. 665,118, dated January 1, 1901;

Application filed May 25. 1900. yserial No. 17,963. (No model.)

To all whom it may concern: I

Be it known that I, LARS M. LANDING,a citi- Zen of the United States, and a resident of Glenwood, in the county of Pope and State of Minnesota, have invented new and useful Improvements in Interest Computing Machines, of which the following is a full, clear, and exact description.

My invention relates to machines for oomputing interest and time, and has for its object to provide a machine of this class which will enable an operator to readily figure the interest on various principals at various rates and for various vtimes and which will also enable the operator to readily ascertain the time (number of days)v between two given dates.

The invention will be fully described hereinafter and the features of novelty pointed out in the appended claims.

Reference is to be had to the accompanying drawings, forming a part of this specification, in which similarcharacters of reference indicate corresponding parts in all the figures.

Figure l is a plan of my improved calculator with parts broken away. Fig. 2 is a crosssection substantially on the line 2 2 of Fig. 4.. Fig. 3 is a detail plan of a locking device with parts in section, and Fig. 4 is a plan of part of the machine drawn upon an enlarged scale.

The machine comprises a base or frame A of any suitable shape-for instance, Octagonal, as shown-and said base carries a top plate A in the shape of a ring surrounding a central circular opening. The top plate is held in proper position relatively to the base A by means of a spacing-strip A2. At one side of the machine a stop or linger B is secured to the top plate A', the inner end of said finger extending beyond the top plate. At the other side the top plate A is provided with a radial slot A3, and along the edge of the slot are produced in a space A4 the words and indications Days, 6%, 7%, S%, 10%, Mo., Day, it being understood that the range of percentages may be varied. The top plate A has also secured to it, adjacent to the slot A3, a supporting-plate A5, provided with a guide and stop A6, engaging the periphery of a disk C, pivoted to said supportingplate at C. ,Corresponding to' the columns in the space A4 lines A7 extend from the slot A3 to the periphery of the disk C, and these lines are adapted to register with the ends of .radial lines C2 upon said disk. The disk is divided into a plurality of sections C3, the width of each section at the periphery being equal to the distance between the outermost lines A7. Adjacent to the periphery the disk has spaces C4, in which are produced numbers indicating the. interest on ten dollars for the number of years indicated at CL at the rates indicated in the space A4. 'lhus if the disk C is turned until the section C3 so lettered in the drawings registers with the lines A7 it will be seen at a glance that the interest on ten dollars for one year is $06, 0.7, 0.8, and 1.0, respectively, at the rates of six, seven, eight, and ten per cent., while the interest for tive years is indicated as $30, 3.5, 4 0,7 and 5.0. The disk C, with the arrangement shown in the drawings, indicates the interest for any number of years from one to eight. The disk may be turned by means of a pointed tool, such as a pencil, inserted into recesses or apertures C5.

To the base A is secured a stationary central pivot D, which extends through a sleeve E, mounted thereon loosely and provided with a plate E', which is secured to a disk F, extending outwardly under the top plate A to within a short distance of the spacing-strip A2. On top of this disk F is loosely mounted a smaller disk G, the periphery of which is adjacent to the inner edge of the top plate A. On the sleeve F. are further loosely mounted a pointer H,having produced upon it the numerals l to 9 in their regular sequence, a washer I, two opposing cam-handles J, another washer I, and a nut K. The handles J are made, as shown in Fig. 2, with annular ribs J', which are wedge-shaped and adapted to engage each other, the obvious effect of turning the handles in one direction consisting in forcing the washerI, pointer H, and disk G down against the disk F, so that both disks will be held to rotate in unison. When, however, the handles are turned in the opposite direction, the pressure will be IOO relieved and the upper disk G will be capable of rotating independently of the lower disk F. The annular ribs J/ of the handles J inclose a space J2, within which is located a spring L, the ends of which take into recesses in the respective handles, the spring assisting in holding the handles in the position shown in Fig. 3. This spring may, however, be omitted.

The lower disk is provided at its periphery with a notch FQ adapted to be engaged by a latch M, pivoted at M' to the base A to hold the disk F in its normal or initial position. The disk F is provided with a series of nu meral-eolumns corresponding and adapted to register with the columns in the space A4 of the top plate A. Thus the outermost ring or column N contains the .numbers of days from 1 to 360, this being` the number of days in an interestyear- The next rings or columns N contain the corresponding amounts of interest at the rates in the space A4, and the columns N2 contain the number of days expressed in months of thirty days and days. Thus when, as in Fig. 1, the disk F is turned to bring the number 116 of the column N into View in the slot A3 there will appear in the columns N2 the equivalent of one hundred and sixteen days-three months and twenty-six days-and in the columns N the interest on ten dollars for one hundred and sixteen days at six, seven, eight, and ten per cent. as 50.1033, 02256, 0.2577, and 03222, respectively. The mills and tenths of mills are given in order that the interest on one hundred dollars and one thousand dollars may be found accurately by simply shifting the period one or two spaces to the right. The upper disk G likewise has a series of concentric rings of fige ures, divided into twelve sectors, bearing the names of the months in the space O. In the outer ring O are disposed the numerals 1 to 30 for each month, (the thirtieth space being left a blank for the month of February,) and in this ring are also provided recesses or apertures P, one for each space, said recesses being adapted to receive a pencil or other pointed tool. At the beginning of the month of January is located a radial line Q, termed and designed as the New-Year line. Preferably the sign is produced adjacent to every month having thirty-one days and the sign adjacent to February. The two rings of figures O2 next to the ring O on the inside contain successive numerals-for instance, those from 1 to 1S0--and the innermost rings O3 are divided into just as many spaces as the rings O2 and contain the multiples (from 1 to 9 of the numbers contained in the inner ring O2. The latter and the eight rings O3 are so arranged as to register with the numerals 1 to 9 on the pointer H. (See Fig. 4.) The top plate A is provided adjacent to the edge of the disk G with a series of numerals A8, running from l to 360, the starting-point being at the stop B.

The manner of using the appliance for finding the interest on ten dollars, one hundred dollars, duc., for any period from one day up to eight years will be obvious. The disk C will give the amount of interest for entire years and the disk F for fractions of a year expressed in days or in months and days. To find the interest on principals which are not multiples of ten, the pointer H and the rings O203 of the disk G are used. Suppose it is desired to lind the interest on two hundred and fifty-seven dollars at six per cent. for a period of one year and two hundred and seventy days. A pencil is then inserted into the aperture C5 of the disk C which is adjacent to the inner number l and the disk is turned until the pencil abuts against the stop Af. The disk will then indicate that the interest on ten dollars for one year is $0.6 at six per cent. The handles J being then broughtinto the diverging position, (shown in Figs. 1 and 3,) so as to lock disks F and G together, the lower disk F is turned by means of the handles J until the number 270 on the outer ring N shows in the slot A" of the top plate A The disk F will then show that the interest on ten dollars at six per cent. for two hundred and seventy days amounts to $0.15. By addition it is therefore found that the interest on ten dollars at six per cent. for one year and two hundred and seventy days amounts to $1.05. Now the pointer Il is turned to register with the number 105 on the inner ring 02 of the disk G. The number 2 of the pointer willthen register with 210 in the outermost ring O3, the number 5 of the pointer will register with 525, and the number 7 with 735. These three numbers, 210, 525,7 and 735, will then be added in the customary way, (partial products of a multiplication,) thus giving 520985 as the interest on twohundred and fifty-seven dollars at six per cent. for one year and nine months, (two hundred and seventy days.) The same result can also be obtained in the following way: The interest on ten dollars at six per cent. for one year and nine months having been found to be one dollar and live cents, as before, the interest on two hundred dollars under the same conditions is written down as $510.5 l- 10.5 and there remains to be found the interest on fifty-seven dollars. For this purpose the pointer H is turned to register with the number 57 on the inner ring O2 of the disk G. The figure l of the pointer will then give the number 57 and the figure 5 of the pointer will give the number IOO This method ol obtaining the result is preferable on account of being applicable in all cases, inasmuch as one of the factors will always be smaller than one hundred.

The machine is also used for ascertaining the number of days between two dates. For this purpose and to ascertain the interest at the same time the lower disk F is iirst brought to the zero position. Then the handles J are turned so as to release the upper disk G, a pencil inserted at the earlier date-say January 3-and the disk G turned around (in the same direction as the hands oi a watch) until the pencil strikes the stop B. Preferably the latch M is thrown in during this operation, so as to prevent an accidental turning of the disk F. Then the handles J are turned in the opposite direction,so as to connect the disks F and G for simultaneous movement, and the latch M is thrown out to release the disk F. rlhe pencil is then inserted into the recess P corresponding to the later date-say July lY-which will bring to the slot A3 of the top plate A the number of days, 194, (six months fourteen days,) and the interest figures 3233, 3772, 4311, and 5389. The numbers in the ring AS are used when the number of days between two dates and one of said dates are given and it is desired to nd the other date. This is done by simply bringing the. given date in registry with the pointer B or with the given number of days in the ring AS, according as the earlier or the later date is given.

In order to find the exact number of days between two dates,there will have to be added one day for every month of thirty-one days, the last day of which is between said dates,and one or two days will have to be deducted if the last day of February is within the calculation.

The improved computing-machine may also be used for solving, at least approximately, various other problems, such as iinding the time during which the interest on a given principal will become equal to a given amount at a given rate.

Having thus described my invention, l claim as new and desire to secure by Letters Patent- 1. An interest-computing machine, comprising a frame having a central opening and a sight-opening or slot adjacent thereto, indications of interest rates adjacent to said sight-opening, a disk mounted to revolve in the frame and having a series of interest iigures for dierent numbers of days, adapted to show through said sight-opening, another disk pivoted about the same axis and bearing around its periphery indications of days and months, and mechanism for connecting said disks to move in unison, or allowing the second-named disk to turn independently.

2. An interest-computing machine, comprising a frame havinga sight opening or slot with indications of interest rates adjacent to said opening, a disk mounted to revolve in the frame and having a series of interest figures for different numbers of days, adapted to show through said sight-opening, and another disk divided by radial lines into sectors and spaces giving the interest at various percentages for diierent numbers of years, said second disk being pivoted to the frame eccentrically in relation to the iirstmentioned disk, and the frame being provided, between the sight-opening and the periphery of the yearly-interest disk, with lines corresponding to the indications of interest rates adjacent to the sight-opening, said lines leading to the periphery oi' the yearly-interest disk and being there separated by distances equal to the width of the spaces on said disk.

3. An interest-computing machine, comprising a frame having a central opening and a sight opening or slot adjacent thereto, indications of interest rates adjacent to said sight-opening, a disk mounted to revolve in the frame and havingaseries of interest gures for different numbers of days, adapted to show through said sight-opening, another disk pivoted about the same axis and bearing around its periphery indications of days and months, two cam-handles mounted on the pivot of said disks and an abutment for the upper cam-handle, so that by turning the handles in one direction the lower handle will be forced lengthwise of the pivot to press the upper disk into firm contact with the lower disk.

4. An interest-computing machine, comprising a frame having a central opening and a sight opening or slot adjacent thereto, indications of interest rates adjacent to said sight-opening, a disk mounted to revolve in the frame and having a series of interest figures for different numbers of days, adapted to show through said sight-opening, another disk pivoted about the same axis and bearing around its periphery indications of days and months, said disk also bearing in concentric rows or rings, a series of numerals in their natural sequence, together with the multiples of said numerals, and a pointer mounted to turn about the pivot of the disks, and provided with a consecutive series of numerals arranged to register with the numbers and multiples on said second disk.

5. An interest-computing machine, comprising a base, a top plate having a central circular opening and a radial sight opening or slot adjacent to the central opening, with indications of interest rates at said opening, and indications of day-numbers around the circular opening, a spacing-strip separating IIO IIS

the top plate from the base, a pivot secured to the base centrally, a sleeve loosely mounted on the pivot, a disk rigidly secured to said sleeve and projecting under the top plate, said disk bearing a series of interest figures for different numbers of days, adapted to show through the sight-opening, another disk loosely mounted on said sleeve and tting within the circular opening of the top plate, said disk bearing around its periphery indications of daysand months, and also bearing in concentric rows or rings, a series of numerals in their natural sequence, together with the multiples of said numerals, a pointer mounted to turn on the sleeve and provided with a consecutive series of numerals arranged to register with the numerals and multiples on said second disk, a nut screwing on the sleeve, and two handles mounted to turn on the sleeve between the said nut and the upper disk and provided with oblique surfaces or cams on their opposing sides, so that by turning the handles in one direction the lower cam-handle and the upper disk will be forced lengthwise of the pivot to clamp the disks together.

6. An interest-computing machine, comprising a base, a top plate having a central circular opening and a radial sight opening or slot adjacent to the central opening with indications of interest rates at said opening, and indications of day-numbers around the circular opening, a disk pivoted to the top plate exteriorly of its central opening and divided by radial lines into sectors and spaces giving the interest at various percentages for different numbers of years, the top plate being provided with lines corresponding to the indications of interest rates adjacent to the seattle sight-opening and leading from said opening to the periphery of said disk, the distance between said lines, at the periphery of the disk, being equal to the peripheral width of the disk-spaces, a spacing-strip separating the top plate from the base, a pivot secured to the base centrally, a sleeve loosely mounted on the pivot, a disk rigidly secured to said sleeve and projecting under the top plate, said disk bearing a series of interest ligures for dilterent numbers of days, adapted to show through the sight-opening, a latch for locking said daily-interest disk, another disk loosely mounted on said sleeve and fitting within the circular opening of the top plate, said disk bearing around its periphery indications of days and months, and also bearing in concentric rows or rings, a series of numerals in their natural sequence, together with the multiples of said numerals, a pointer mounted to turn on the sleeve and provided with a consecutive rseries of numerals arranged to register with the numerals and multiples on said second disk, a nut screwing on the sleeve, and two handles mounted to turn on the sleeve between the said nut and the upper disk and provided with oblique surfaces or cams on their opposing sides, so that by turning the handles in one direction the lower cam-handles and the upper disk will be forced lengthwise of the pivot to clamp the two disks together.

ln testimony whereof I have signed my name to this specification in the presence ol' two subscribing witnesses.

LARS M. LANDING.

Witnesses:

HAROLD SwENsoN, MARTIN LUNDQUIs'r. 

